The present invention relates to a steam relieving safety valve assembly for a water-cooled type nuclear reactor in which water is used as a primary coolant, and a method of confirming the operation or functioning of a steam relieving safety valve of the water-cooled type nuclear reactor from a remote location without delay and without fail.
Regulations require the installation of a steam relieving safety valve (referred to simply as "safety valve", hereinafter) on boilers to relieve the internal pressure when it is increased in a level 6% higher than the maximum operation pressure.
In case of water-cooled nuclear reactors, it is necessary to make some suitable measure for confirming the safe operation of the safety valve attached to a steam drum from a remote location, because the safety valve, which is installed in an environment of high temperature and high level of radioactivity, is inaccessible.
Hitherto, the confirmation of operation of the safety valve has been made by means of a thermocouple disposed in a steam relief pipe leading from the safety valve so as to detect the temperature rise due to the blow out of the steam, i.e. the functioning of the safety valve. This conventional method, however, has a drawback that the operation of the safety valve for a short period of time cannot be correctly sensed because of the poor response characteristic of the thermocouple attributable to the large time constant thereof.